Forced-draft apparatus.



f N0. 703,539. Patented 'my 1902.

. J. s. CHAPMAN...

FCIBIIED DRAFT APPARATUS.

(Application led Mar. 3,'1902.) (lo Medel.)

UNITED STATES PATENT OEEICE.

JOHN S. CHAPMAN, OF ALBANY, NEIV YORK.

FORCED-DRAFT APPARATUS.

SPECIFICATION forming part of Letters Patent No. 703,539, dated July 1, 1902.

Application filed March 3, lQQZ. SerialNo. 96,490. (No model.)

-form a part of this specification.

The object of my invention is to provide a new and improved forced draft for steamboilers and one in which a portion of the heated gases from the chimney or stack is used in connection therewith. l

In the drawings, Figure l shows a front elevation ofa steam-boiler, preferably of the tubular return type; Fig. 2, a vertical section of the same seen from the rear; Fig'. 3, a vertical section of the steam-receiving box Fig. 4, a vertical sectional view of the superheaters; and Fig.l 5, a vertical sectional view of thelower end of the box 4, showing the airentrances thereto. 4

The numeral l shows theboiler-front, and 2 the stack.

The pipe or flue 3 is connected with the stack in any desired manner and is carried to the top of the steam-receiving box or chamber 4-and is in operative connection there-V with, preferablyl as seen in Fig. l.

8 shows the steam-dome of the boiler, from which leads the steam-pipe S', passing into and through the walls of the furnace, preferably at a point just back of the fire-bridge I6, (see Fig. 2,) and is there connected to the superheaters 9 9, and from thence is carried by steam-pipe IO to the vertical pipe 6 and into the perforated pipes 13, inside thesteamreceiving box or chamber-4, the. perforations.

that pipe, as the escaping steam l2 produces a more or less -perfect vacuum in the steamreceiving box 4.

7 shows a damper in pipe 3.

5 indicates a movable blind or cover for the bottom of box 4, said box-bottom having openin Us therein, as seen at 5' and the blind also as seen at 5, the registering of the openings letting the air in. As shown in Fig. 5, the .openings are closed; The blind 5 has a vthreaded rod 5 protruding from the box, as

of a box or hollow bottom and tubes 9',

screwed or otherwise fastened thereto and having a baiiie-plate 9 therein, so as to compel the steam as it enters, as indicated by the arrows', to pass to the top of the tube and then ,down'into the box and up and down the succeeding tubes, compelling it to travel a long circuitous route through the superheater,

Ithereby not only superheating it, but separatin git from any ent-rained water it may contain. If desired, the places of the baffle-plates 9 maybe taken by steam-pipes connected with-ibase, so as to produce the same general course of the steam. As the superheater stands on or just back of the fire-bridge 16, it receives the heat from the gases and iiame asthey pass over the bridge and becomes highly heated.

The operation is as follows: The valve in steam-pipe 8 being opened, the steam from the boiler passes to the superheater 9 and vmakes the cireuitous path through the same (indicated by the arrows in Fig. 4) and .from thence through steam-pipe 10 to vertical pipe 6 and from thence out of the perforated` pipes 13 and through an opening in the side of the furnace-wall to a point under the grate-bars Il. As it passes with greatforce and swiftness through the steam-receiving box 4, it creates a partial vacuum in that box, which creates a downdraft in the pipe Sand draws through it and under the grate-bars ll more or less of the smoke and heated gases from the smoke-stack 2, and the open- IOO when my apparatus is being used. When my apparatus is not desired to loe used, the valve in steam-pipe 8 may be closed and the ash-pit doors opened, when the re will receiveits supplyof air in the ordinary manner.

Having described my invention, what I claim is- 1. In asteam-boiler a conduit leading from the smoke-stack into a receptacle in connection with the space under the grate-bars; a baiiie-plate in proximity to the lower end of the said conduit; asteam-pipe in connection with the boiler discharging in the said receptacle and practically across the dischargemouth of the conduit so as t-o converge the steam at a predetermined point and means for admitting air to said receptacle in predetermined quantities, in order that a portion of the hot gases from the smoke-stack and a portion of the steam from the boiler and some air may be forced into and through the fire on the grates substantially as described.

2. A superheated-steam-draft-forcing device consisting of a conduit leading from the smoke-stack of a boiler to and discharging into a receptacle; a steam-pipe leading from the boiler to and discharging into said receptacle and practically across the mouth of the conduit; said steam-pipe being connected with a superheateil arranged to receive the heat from the furnace-fire and superheat the steam as it passes through the same; means whereby the steam is caused to make a circuitous path through the superheater and means for admitting air to the said receptacle and mix it with the steam from the boiler and the heated gases from the smoke-stack and discharge them under the fire-grate substantially as described.

3. In an apparatus for producing draft by superheated steam, heated gases and air, consisting of a conduit leading from the smokestack to a receptacle; a steam-pipe leading from the boiler to said receptacle through a superheater located at the fire-bridge and arranged to receive the heat of the furnace as it passes the fire-bridge; means for introducing air to the receptacle and means for producing a downdraft in the conduit and for forcing the contents of the receptacle under the grate-bars under pressure substantially as described.

In testimony whereof I affix my signature in presence of two witnesses.

JOHN S. CHAPMAN.

Witnesses:

A. M. TURNER, JAS. M. BROWN. 

